no it doesnt kill performance - its the nvidia 7300 that does this- like i said. the nvidia 7300 is really stretched doing mulitple outputs.
i have had to replace several with x1900 on shows.
it works fine with x1900. it works fine doing 1080i providing you are not trying to do to many other things at the same time
video input REQUIRES careful consideration of playback, and conservative operation.
you need to replace your 7300.